Earth

Earth is the only planet currently known to humans are living beings. The Earth's diameter is 12,756 km (at the equator). The distance from Earth to the sun about 150 million km. This distance is known as an astronomical unit (AU).

Earth is the third planet from the eight planets in the Solar System. Differences with Venus and Mercury, is not a natural satellite of Earth, or the moon. Moon is always around the Earth revolves around the sun. Earth rotates at 23.9 hours, and evolved over 365.3 days.

Inner Earth

Earth set to be done in the earth's core is composed of iron-nickel 1370 km thick frozen at temperatures 4500 ° C, is also covered by an outer core liquid which is 2100 km thick, and also covered by the mantle 2800 km thick silica to form 83% of the land, and eventually completely covered by the Earth's crust about 85 kilometers thick.

The crust is thinner on the seabed, which is about 5 km. The crust is divided into several parts and movement through the motion of tectonic plates (the theory of continental drift) that produce earthquakes.